In a wireless or mobile communication system, including multiple access systems such as code division multiple access (“CDMA”), CDMA 2000, wideband CDMA (“WCDMA”), time-division multiple access (“TDMA”) systems such as GSM (global system mobile), other cellular or PCS communication systems, wireless local area networks (“WLAN”), mobile IP (internet protocol) systems, and other wireless networks, interconnection facilities contribute a significant portion of the fixed costs of an operator or other service provider. Such interconnection facilities are used both to establish and to handoff or transfer communication sessions, as mobile units (subscribers) move about within geographic coverage regions, between and among core network facilities and access networks. A core network, as that terminology is used herein, is to be construed broadly to mean and include any and all network facilities having switching, routing, or other intelligent functions. A core network may typically include, for example, one or more facilities or devices such as wireline switches, mobile switching centers (“MSCs”), softswitches (circuitless switching exchanges), call agents (voice over packet call control entities), application servers of IP networks, packet routers, home agents and foreign agents for mobile IP, visitor location registers (“VLRs”), intelligent nodes such as service control points (“SCPs”), a service circuit nodes (“SCNs”) (or service nodes), an intelligent peripheral (“IP”), packet data serving nodes (“PDSN”) (e.g., in CDMA2000), GSM switching centers or nodes, generalized packet radio service (“GPRS”) nodes (global GPRS support nodes (“GGSNs”) and serving GPRS support nodes (“SGSNs”), and similar devices. An access network (“AN”), as used herein, is also to be interpreted broadly, to mean and include devices which provide a direct information link to one or more mobile units or mobile stations, such as for the transmission and reception of communication sessions with mobile units, such as for voice, data, multimedia, or any other information. For example, an access network may include one or more facilities or devices such as base station controllers (“BSCs”), base transceiver stations (“BTSs”) (or equivalent transceivers and controllers), along with other access equipment used to communicate wirelessly in any system, such as base stations supporting WLAN air interfaces (in wireless LAN systems), wireless LAN access points, and any other devices which send and receive data to and from mobile units. The information transmitted or received may be of any type or kind, under any applicable protocol, including analog, digital, spread spectrum, and so on. The mobile units (or mobile stations) may be of any type or kind, such as cellular, CDMA or 3G communication devices, mobile computers, personal digital assistants, and so on.
Typically, to facilitate such session establishment or handoff, core network interconnect (often referred to as backhaul transport facilities) are used to provide connections among the core network facilities, and access network (AN) interconnect (often referred to as side-haul transport facilities) are used to provide connections among the access networks.
As mobile units traverse a geographic region, or during a re-routing of sessions (including packet sessions), the point of access to the communication network (for the other, remote end or portion of the communication session) typically remains constant, requiring voice and data traffic to be transported between and among the various core network (and access network) facilities for continuation of the communication session. For example, for a session to or from the public switched telephone network (“PSTN”), a mobile switching center providing such fixed access to the PSTN for a given session is typically referred to as an anchor (or originating) MSC (or GGSN), while the MSC providing service to the roaming mobile unit is typically referred to as a serving MSC (or SGSN). As mobile units traverse geographic regions within the coverage of a single switch or node, handoffs typically occur between the coverage areas of the access networks, such as base station transceivers, including soft handoffs of CDMA systems.
As indicated above, these transport facilities typically entail significant fixed costs, which vary depending upon the nature of the facilities, tariffing, whether they are public, leased, or operator owned, and so on, and it is important for the operator to utilize these facilities most efficiently and at a lowest cost, while nonetheless providing desired or requested levels of service. As a consequence, path optimization is utilized to determine an efficient or a most efficient path through the core network, the interconnect, and the access networks, to establish and maintain the communication session through one or more handoffs or other re-routing.
In the prior art, such path optimization is performed solely by the core network, such as the MSCs, wireline switches, or the network routers. In circuit-switched networks, factors utilized in path optimization (trunk or route selection) typically include time of day considerations, holidays, and tariff cost minimization. In packet and internet protocol (IP) routing, routers typically utilize a least cost routing algorithm, such as OSPF (Open Shortest Path First).
In GSM systems, path optimization is performed in a hierarchical manner, with base station equipment performing path choices for transceivers within its control, with all other path choices performed at the higher switch or node level.
None of these methods of path optimization provide truly optimal routing choices, under potentially changing circumstances, and given potentially changing requirements for any given communication session. As a consequence, a need exists for a method and system to provide network path (or routing) optimization, which accounts for these changing circumstances, and which affords distributed control over path decisions.